Trump announced Thursday that his administration would immediately stop implementing the 195-nation accord brokered by Barack Obama in 2015 in tandem with Chinese leaders.

The European Union said it was increasing efforts with China, the world's biggest polluter, to galvanise global efforts to implement the deal while India vowed to stick to the pact regardless of the United States.

Trump also faced a backlash at home where Democratic state governors, city mayors and powerful companies drew up plans to meet the pact's greenhouse gas emission targets.

"Americans will honour and fulfill the Paris agreement by leading from the bottom up -- and there isn't anything Washington can do to stop us," former New York mayor and billionaire Michael Bloomberg said.

However, Russian President Vladimir Putin spared Trump more withering criticism and urged the world to work with the New York tycoon on climate.

In Brussels, European Council President Donald Tusk said the EU is "stepping up our cooperation on climate change with China" following a summit with Chinese Premier Li Keqiang.

But EU officials said the two sides failed to formally endorse a joint statement on the issue due to a lingering but separate trade row.

Expressions of shock and regret poured in from around the world, including from Pacific islands at risk of being swallowed by rising seas, who accused Washington of "abandoning" them.

In a nationalistic "America First" announcement from the White House Rose Garden, Trump said he was withdrawing from a UN-backed deal that imposes "draconian financial and economic burdens" on the United States while going too easy on economic rivals China, India and Europe.

"We don't want other leaders and other countries laughing at us anymore. And they won't be."

Trump offered no details about how, or when, a formal withdrawal would happen. At one point he suggested a renegotiation could take place, an idea that was unceremoniously slapped down by partners.

The United States is the world's second-largest greenhouse gas emitter, after China, so Trump's decision could seriously hamper efforts to cut emissions and limit global temperature increases.

Nicaragua and war-torn Syria are the only countries not party to the Paris accord, the former seeing it as not ambitious enough.

Trump's decision is likely to play well with the Republican base, with the more immediate damage likely to appear on the diplomatic front.

Vice President Mike Pence said that Trump "has demonstrated his commitment... to put American workers, American consumers, American energy, and the American people first."

Echoes of reality TV

Ever the showman, the 70-year-old Trump gave his decision a reality TV-style tease, refusing to indicate his preference either way until his announcement.

Opponents of the pullout -- also believed to include Trump's daughter Ivanka -- had warned that Washington's global leadership role was at stake, along with the environment.

A dozen large companies including oil major BP, agrochemical giant DuPont and tech heavyweights Google, Intel and Microsoft had urged Trump to stick to the pact.

Following the announcement Tesla boss Elon Musk and Disney chief Robert Iger said they would no longer participate in presidential business councils.

"Climate change is real. Leaving Paris is not good for America or the world," Musk said.

'Morally criminal'

White House officials acknowledged that under the deal, a formal withdrawal might not take place until after the 2020 election, and leaders will certainly push Trump to reconsider his decision in the meantime.

India's environment minister Harsh Vardhan said his country is committed to the Paris accord "irrespective" of the position of other nations.

Indian Prime Minister Narendra Modi -- who has said failing to address climate change would be "morally criminal" -- is due to visit the White House shortly.

Trump's announcement comes less than 18 months after the climate pact was adopted, the fruit of a hard-fought agreement between Beijing and Washington under Obama's leadership.

The Paris Agreement commits signatories to efforts to reduce greenhouse gas emissions that cause global warming, which is blamed for melting ice caps and glaciers, rising sea levels and an increase in extreme weather events.

They vowed to take steps to keep the worldwide rise in temperatures "well below" two degrees Celsius (3.6 degrees Fahrenheit) from pre-industrial times and to "pursue efforts" to hold the increase under 1.5 degrees Celsius.